If it were possible to perfectly fabricate a data conversion circuit, such as an analog-to-digital converter (ADC) or digital-to-analog converter (DAC), from ideal elements, the data conversion circuit could perform in a fully and precisely accurate manner. However, non-ideal circumstances can impair performance of a practicable data conversion circuit.
For example, in a radar system, harmonic distortion in an ADC can cause intermodulation distortion (IMD) products, which can appear as false targets returned by the radar system. When, for example, such a radar system is used to control braking of a vehicle, the false targets can activate an automatic braking feature, stopping the vehicle for no apparent reason.
Harmonic distortion in a continuous-time sigma-delta modulator, as may be found in a sigma-delta ADC, is caused primarily by element mismatch in the DAC current sources. This is a well-known problem and is usually addressed using dynamic element matching techniques. However, such dynamic element matching techniques can have undesirable consequences, such as increasing semiconductor die area occupied by the circuit, increasing power consumption, increasing noise generation, causing excess loop delay giving rise to stability concerns. Thus, a technique that avoids such disadvantages would be a technological improvement over existing technology.
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